Make swapping second stages fast and tool-free. The XS Scuba AC991 is the male quick-disconnect fitting designed to pair with XS Scuba’s second-stage QD system—perfect for divers who switch between an octo, primary, or full face mask setups.

If you run multiple second stages or switch between different regulator configurations, the XS Scuba AC991 makes it simple. This low-pressure (LP) second stage quick disconnect male fitting installs on an additional second stage so you can snap it into your hose-side QD and swap regulators quickly—without breaking out wrenches or risking twisting fittings during changes.

Built from durable chrome-plated brass with Viton O-rings, the AC991 is a rugged, reliable solution for recreational divers, instructors, and public safety divers who want faster gear changes, easier travel packing, and a cleaner way to manage multiple second stages. Designed for LP use only (below 200 psi / 13.8 bar).

Key features

Male-only QD fitting (add one to each additional second stage)

Enables quick swaps between second stages without tools

Chrome-plated brass construction for long service life

Viton O-rings for dependable sealing

Low-pressure only (intermediate pressure applications)

Specs

Part number: AC991

Type: 2nd stage hose quick disconnect (male fitting)

Pressure rating: LP use only — below 200 psi (13.8 bar)

Material: chrome-plated brass

Seals: Viton O-rings